The metabolic and hormonal control of food intake in man will be studied during experimental hunger induced by glucopenia and food deprivation. The contributions of peripheral catecholamines to the development of hunger and thirst will be assessed in cervical cord sectioned and adrenalectomized patients. The importance of renal renin in the extracellular control of thirst will be determined in nephrectomized man. Studies involving normal weight and obese subjects will help delineate the role of cognitive and/or metabolic factors controlling food intake. Potential anorectic agents will be evaluated as to their neuropharmacological model of action in normal weight and obese subjects and the results will be correlated with alterations of feeding patterns. Prior to and following varying periods of caloric deprivation feeding patterns will be examined in lean and obese subjects utilizing an electronically activated feeding machine. Comparison of meal patterns will be made under similar conditions, where either liquid or solid diets are consumed. In addition, by self-feeding via nasogastric tube, the role of oropharyngeal factors known to influence food intake may be clarified. Lastly, effects of various intragastric nutrient loads varying in nutrient composition on meal patterns will be examined.